Overview
G2a2a (M286) represents one of the earliest diverging branches within G2a2 and is an essential Near Eastern and Caucasian lineage predating the major G2a2b (P303/L30) Neolithic expansions. It captures the genetic landscape of early Holocene highland and foothill populations in regions stretching from eastern Anatolia to the central and southern Caucasus. Unlike the heavily Neolithic-associated G2a2b, G2a2a maintains a deep-time Asian–Anatolian profile reflective of pre-agricultural and early proto-agricultural societies.
Despite being overshadowed by the numerical dominance of G2a2b in ancient European genomes, M286 provides critical evidence of older West Asian paternal structure. Its descendants appear sporadically in modern populations but with notable continuity in the Caucasus, Iranian Plateau, and northern Mesopotamia.
Geographic distribution
G2a2a is most prevalent in the Caucasus (Georgia, Armenia, Dagestan), eastern Turkey, and parts of northwest Iran. It appears at low frequencies in the Levant and is exceptionally rare in Europe, where it is largely overshadowed by the G2a2b radiations. Modern distributions suggest long-term refugial continuity in highland regions, where early post-glacial populations persisted.
Scattered presence in the Mediterranean and Europe usually reflects isolated founder events or historical migration rather than deep-time continuity.
Ancient DNA
- A limited number of ancient genomes from the Caucasus highlands and eastern Anatolia exhibit upstream variants consistent with G2a2a ancestry.
- Pre-Pottery Neolithic sites in the northern Fertile Crescent show tentative upstream SNP associations suggesting early G2a2a-like lineages.
- G2a2a has not been conclusively identified in European Neolithic genomes, reinforcing its Near Eastern-centered distribution.
Phylogeny & subclades
G2a2a diverges early from the G2a2 stem, forming a trunk that predates the major G2a2b radiation. Its internal structure is moderate, containing regional microclades concentrated in the Caucasus and Iranian Plateau. Basal diversity suggests a split within the central-to-eastern Anatolia highland region, with subsequent stability rather than large-scale expansion.
- G2a2a* (basal M286)
- Caucasus-centered microclades
- Near Eastern–Iranian sub-branches
Notes & context
G2a2a preserves an essential layer of early West Asian paternal ancestry that predates the expansionary Neolithic wave. For a mega haplogroup atlas, it provides the foundation for understanding how early highland and foothill populations contributed to later farmer societies even when not directly represented in European ancient DNA.
References & external links